Michaela Whitbourn, Kate McClymont

The barrister leading the Independent Commission Against Corruption inquiry has raised questions about whether the information leading to Premier Barry O’Farrell’s resignation was strategically leaked to the media to bring him down.

In the final minutes of a marathon 23-day inquiry into a company linked to the Obeid family, the man who admitted he gave Mr O’Farrell the Penfolds Grange Hermitage was challenged about how the media knew about the undeclared gift ‘‘before ICAC did’’.

Former Australian Water Holdings chief executive Nick Di Girolamo, a Liberal Party fund-raiser and an associate of the Obeid family, was asked whether he had told the former Liberal energy minister Chris Hartcher about the gift of a $3000 bottle of wine, which was sent by courier to the Premier’s Roseville home on April 20, 2011.

Mr O’Farrell wrote back: ‘‘Confirm no recollection or record of the alleged gift.’’ Mr Hartcher quit the cabinet in December last year after ICAC investigators raided his Central Coast office over a separate inquiry into political donations, which is due to start hearings on April 28.

The inquiry has heard allegations that Mr Di Girolamo had arranged for AWH to make ‘‘regular payments’’ to a slush fund linked to Mr Hartcher in exchange for favourable treatment from the minister.

In a statement on Thursday morning, Mr Hartcher denied that he was the source of the leak.

"Accusations that I am the source of the leak concerning the $3000 bottle of wine are incorrect and scurrilous," Mr Hartcher wrote.

"I had no prior knowledge about a gift of wine sent to the then Premier, Barry O'Farrell and any suggestion otherwise is false.

"The first I was made aware of the bottle of wine was upon reading about it in the media. I have no further comment to make."

Mr O’Farrell’s resignation followed his unequivocal denial on Tuesday that he had received the $3000 bottle of wine from Mr Di Girolamo shortly after the election.

Overnight, Mr Di Girolamo discovered a thank you note he had received from the Premier following the gift of wine, prompting Mr O’Farrell to resign at about 10am on Wednesday.

Mr O’Farrell insisted he still had no recollection of the wine or of writing the note. Later in the day, Mr Watson moved to quash speculation that the commission had sat on the note in order to trap Mr O’Farrell, saying the information was received at 9.17am in the morning from Mr Di Girolamo’s barrister.

Mr O’Farrell’s demise was never regarded as one of the likely consequences of ICAC’s inquiry into AWH.

The commission is investigating allegations that the family of the corrupt former Labor minister Eddie Obeid were ‘‘secret stakeholders’’ in AWH, and that Mr Obeid had improperly lobbied colleagues to favour the company.

Mr Obeid’s former ministerial colleagues Joe Tripodi and Tony Kelly allegedly doctored a cabinet minute in 2010 to support a public-private partnership proposal by AWH.

The cabinet minute was later withdrawn at the insistence of then premier Kristina Keneally. The commission is also investigating AWH’s unsuccessful attempts to lobby the O’Farrell government after the 2011 election to secure the PPP.

Mr Watson this week accused Mr Di Girolamo of being an ‘‘old-fashioned shyster fraudster’’ over separate allegations that Australian Water had billed the public utility Sydney Water for millions of dollars in dubious expenses under a contract to supply infrastructure in the north-west of Sydney.